To create a footnote you will go into the TEXT view and use the simple HTML superscript tag on the number, then put the reference at the bottom of the page

Example of how it looks in the TEXT view:
This is the text. ¹

In the VISUAL view, it will look like this:
This is the text. ¹

This is the footnote at the bottom of the page: (<hr /> tag created the line above)

1. This quote came from Encyclopedia Britannica, Edition 9, 2001